A halogen-containing resin as represented by a polyvinyl chloride resin is blended with a Ca—Zn based or Ba—Zn based stabilizer before being molded, and such molded articles are extensively used for a general purpose as well as foods, medical applications and the like.
However, since these stabilizers can insufficiently inhibit thermal deterioration of a halogen-containing resin, they have drawbacks such as coloration of a molded article immediately after molding and insufficient thermal stability during molding. Therefore, as a means for eliminating the drawbacks, there have been proposed halogen-containing resin compositions containing an antioxidant and/or a hydroxyl-containing compound.
Patent Reference No. 1 (JP 50-92947A) has disclosed a method of adding calcium soap, zinc soap, polyol or a derivative thereof, and a neutral inorganic calcium salt to a chlorine-containing resin.
Patent Reference No. 2 (JP 54-81359A) has disclosed a method of adding a water-soluble polymer to a chlorine-containing polymer.
Patent Reference No. 3 (JP 57-147552A) has disclosed a method of adding a condensation product of dipentaerythritol with a dicarboxylic acid, a zinc compound and hydrotalcite to a chlorine-containing resin.
Patent Reference No. 4 (JP 60-238345A) has disclosed a method of adding a saponified product of an ethylene-vinyl acetate copolymer having an ethylene unit content of from 20 to 50% and a saponification degree of a vinyl acetate unit of 96% or more, and a hydrotalcite-based compound to a thermoplastic resin such as a polyvinyl chloride.
Patent Reference No. 5 (JP 1-178543A) has disclosed a method of adding metal soap and a saponified product of an ethylene-vinyl acetate copolymer having a copolymer composition with an ethylene content of from 20 to 75 mol % and a saponification degree of vinyl acetate unit of 50 mol % or more to a halogen-containing thermoplastic resin.
Patent Reference No. 6 (JP 6-287387A) has disclosed a method of adding a metal salt of an organic acid and acetalized polyvinyl alcohol to a vinyl chloride-based resin.
Patent Reference No. 7 (JP 9-3286A) has disclosed a method of adding partially saponified polyvinyl alcohol having a saponification degree of from 70 to 95 mol %, having an average polymerization degree of from 300 to 2,000 and having a terminal mercapto group to a vinyl chloride-based resin.
Patent Reference No. 8 (JP 9-31281A) has disclosed a method of adding a zinc compound, hydrotalcites, polyvinyl alcohol, and polymethyl methacrylate to a vinyl chloride-based resin.
Non-Patent Reference No. 1 (Japanese Journal of Polymer Science and Technology Vol. 47, No. 3, p. 197 (1990)) has disclosed a method of adding zinc stearate-calcium stearate complex soap and completely saponified polyvinyl alcohol having a polymerization degree of 600 or more to polyvinyl chloride.
Non-Patent Reference No. 2 (Japanese Journal of Polymer Science and Technology Vol. 47, No. 6, p. 509 (1990)) has disclosed a method of adding zinc stearate-calcium stearate complex soap and partially saponified polyvinyl alcohol having a polymerization degree of 500 and having a saponification degree of 73.6 mol % to polyvinyl chloride.
Non-Patent Reference No. 3 (Japanese Journal of Polymer Science and Technology Vol. 50, No. 2, p. 65 (1993)) has disclosed a method of adding zinc stearate-calcium stearate complex soap and an ethylene-vinyl alcohol copolymer having an ethylene content of 29 mol % or more to polyvinyl chloride.
Non-Patent Reference No. 4 (Polymers & Polymer Composites, Vol. 11, p. 649 (2003)) has disclosed a method of adding zinc stearate-calcium stearate complex soap, and polyvinyl alcohol having a polymerization degree of 500 and having a saponification degree of 98.5 mol % or an ethylene-vinyl alcohol copolymer having an ethylene content of 29 mol % or more to polyvinyl chloride.
Non-Patent Reference No. 5 (Journal of the Adhesion Society of Japan Vol. 43, No. 2, p. 43 (2007)) has disclosed a method of adding polyvinyl alcohol having a polymerization degree of 500 and having a saponification degree of 88 mol % or polyvinyl alcohol having a polymerization degree of 1700 and having a saponification degree of 78 mol % or more, and polymethyl methacrylate to polyvinyl chloride.
The halogen-containing resin compositions described in Patent Reference Nos. 1 to 8 and Non-patent Reference Nos. 1 to 5 have the following problems.
Specifically, when a low-molecular-weight polyol is added, the low-molecular-weight polyol bleeds out in the surface during molding, which tends to cause troubles such as adhesion of a kneaded material to a screw surface inside of an extruder or the like during kneading. Furthermore, a molded article obtained tends to have troubles such as volatilization of a polyol, occurrence of blocking, reduction in transparency and reduction in adhesiveness and adherence.
When a high-molecular-weight polyol is added, dispersity of the high-molecular-weight polyol in a halogen-containing resin composition is insufficient, leading to insufficient thermal stability, particularly in molding at a relatively lower temperature.